Increase the retry delay for throttling errors on Azure SQL. (#31612)

Increase the retry delay for throttling errors on Azure SQL.
Detect Azure SQL server based on connection string.
Detect more transient errors.

Fixes #27826

Author: AndriySvyryd

src/EFCore.SqlServer/Extensions/SqlServerDbContextOptionsBuilderExtensions.cs

@@ -41,11 +41,7 @@ public static DbContextOptionsBuilder UseSqlServer(
     {
         ((IDbContextOptionsBuilderInfrastructure)optionsBuilder).AddOrUpdateExtension(GetOrCreateExtension(optionsBuilder));
 
-        ConfigureWarnings(optionsBuilder);
-
-        sqlServerOptionsAction?.Invoke(new SqlServerDbContextOptionsBuilder(optionsBuilder));
-
-        return optionsBuilder;
+        return ApplyConfiguration(optionsBuilder, sqlServerOptionsAction);
     }
 
     /// <summary>
@@ -68,11 +64,7 @@ public static DbContextOptionsBuilder UseSqlServer(
         var extension = (SqlServerOptionsExtension)GetOrCreateExtension(optionsBuilder).WithConnectionString(connectionString);
         ((IDbContextOptionsBuilderInfrastructure)optionsBuilder).AddOrUpdateExtension(extension);
 
-        ConfigureWarnings(optionsBuilder);
-
-        sqlServerOptionsAction?.Invoke(new SqlServerDbContextOptionsBuilder(optionsBuilder));
-
-        return optionsBuilder;
+        return ApplyConfiguration(optionsBuilder, sqlServerOptionsAction);
     }
 
     // Note: Decision made to use DbConnection not SqlConnection: Issue #772
@@ -132,11 +124,7 @@ public static DbContextOptionsBuilder UseSqlServer(
         var extension = (SqlServerOptionsExtension)GetOrCreateExtension(optionsBuilder).WithConnection(connection, contextOwnsConnection);
         ((IDbContextOptionsBuilderInfrastructure)optionsBuilder).AddOrUpdateExtension(extension);
 
-        ConfigureWarnings(optionsBuilder);
-
-        sqlServerOptionsAction?.Invoke(new SqlServerDbContextOptionsBuilder(optionsBuilder));
-
-        return optionsBuilder;
+        return ApplyConfiguration(optionsBuilder, sqlServerOptionsAction);
     }
 
     /// <summary>
@@ -249,6 +237,18 @@ private static SqlServerOptionsExtension GetOrCreateExtension(DbContextOptionsBu
         => optionsBuilder.Options.FindExtension<SqlServerOptionsExtension>()
             ?? new SqlServerOptionsExtension();
 
+    private static DbContextOptionsBuilder ApplyConfiguration(DbContextOptionsBuilder optionsBuilder, Action<SqlServerDbContextOptionsBuilder>? sqlServerOptionsAction)
+    {
+        ConfigureWarnings(optionsBuilder);
+
+        sqlServerOptionsAction?.Invoke(new SqlServerDbContextOptionsBuilder(optionsBuilder));
+
+        var extension = (SqlServerOptionsExtension)GetOrCreateExtension(optionsBuilder).ApplyDefaults(optionsBuilder.Options);
+        ((IDbContextOptionsBuilderInfrastructure)optionsBuilder).AddOrUpdateExtension(extension);
+
+        return optionsBuilder;
+    }
+
     private static void ConfigureWarnings(DbContextOptionsBuilder optionsBuilder)
     {
         var coreOptionsExtension

src/EFCore.SqlServer/Infrastructure/Internal/SqlServerOptionsExtension.cs

@@ -11,10 +11,11 @@ namespace Microsoft.EntityFrameworkCore.SqlServer.Infrastructure.Internal;
 ///     any release. You should only use it directly in your code with extreme caution and knowing that
 ///     doing so can result in application failures when updating to a new Entity Framework Core release.
 /// </summary>
-public class SqlServerOptionsExtension : RelationalOptionsExtension
+public class SqlServerOptionsExtension : RelationalOptionsExtension, IDbContextOptionsExtension
 {
     private DbContextOptionsExtensionInfo? _info;
     private int? _compatibilityLevel;
+    private bool? _azureSql;
 
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -52,6 +53,7 @@ protected SqlServerOptionsExtension(SqlServerOptionsExtension copyFrom)
         : base(copyFrom)
     {
         _compatibilityLevel = copyFrom._compatibilityLevel;
+        _azureSql = copyFrom._azureSql;
     }
 
     /// <summary>
@@ -105,6 +107,50 @@ public virtual SqlServerOptionsExtension WithCompatibilityLevel(int? compatibili
         return clone;
     }
 
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    public virtual bool IsAzureSql
+        => _azureSql ?? IsAzureSqlDefault;
+
+    private bool IsAzureSqlDefault
+        => (ConnectionString ?? Connection?.ConnectionString)
+            ?.Contains(".database.windows.net", StringComparison.InvariantCultureIgnoreCase) == true;
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    public virtual SqlServerOptionsExtension WithAzureSql(bool enable)
+    {
+        var clone = (SqlServerOptionsExtension)Clone();
+
+        clone._azureSql = enable;
+
+        return clone;
+    }
+
+    /// <inheritdoc/>
+    public virtual IDbContextOptionsExtension ApplyDefaults(IDbContextOptions options)
+    {
+        if (!IsAzureSql)
+        {
+            return this;
+        }
+
+        if (ExecutionStrategyFactory == null)
+        {
+            return WithExecutionStrategyFactory(c => new SqlServerRetryingExecutionStrategy(c));
+        }
+
+        return this;
+    }
+
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
     ///     the same compatibility standards as public APIs. It may be changed or removed without notice in

src/EFCore.SqlServer/Infrastructure/SqlServerDbContextOptionsBuilder.cs

@@ -29,7 +29,7 @@ public SqlServerDbContextOptionsBuilder(DbContextOptionsBuilder optionsBuilder)
     /// </summary>
     /// <remarks>
     ///     <para>
-    ///         This strategy is specifically tailored to SQL Server (including SQL Azure). It is pre-configured with
+    ///         This strategy is specifically tailored to SQL Server (including Azure SQL). It is pre-configured with
     ///         error numbers for transient errors that can be retried.
     ///     </para>
     ///     <para>
@@ -48,7 +48,7 @@ public virtual SqlServerDbContextOptionsBuilder EnableRetryOnFailure()
     /// </summary>
     /// <remarks>
     ///     <para>
-    ///         This strategy is specifically tailored to SQL Server (including SQL Azure). It is pre-configured with
+    ///         This strategy is specifically tailored to SQL Server (including Azure SQL). It is pre-configured with
     ///         error numbers for transient errors that can be retried.
     ///     </para>
     ///     <para>
@@ -67,7 +67,7 @@ public virtual SqlServerDbContextOptionsBuilder EnableRetryOnFailure(int maxRetr
     /// </summary>
     /// <remarks>
     ///     <para>
-    ///         This strategy is specifically tailored to SQL Server (including SQL Azure). It is pre-configured with
+    ///         This strategy is specifically tailored to SQL Server (including Azure SQL). It is pre-configured with
     ///         error numbers for transient errors that can be retried.
     ///     </para>
     ///     <para>
@@ -87,7 +87,7 @@ public virtual SqlServerDbContextOptionsBuilder EnableRetryOnFailure(ICollection
     /// </summary>
     /// <remarks>
     ///     <para>
-    ///         This strategy is specifically tailored to SQL Server (including SQL Azure). It is pre-configured with
+    ///         This strategy is specifically tailored to SQL Server (including Azure SQL). It is pre-configured with
     ///         error numbers for transient errors that can be retried, but additional error numbers can also be supplied.
     ///     </para>
     ///     <para>
@@ -116,4 +116,11 @@ public virtual SqlServerDbContextOptionsBuilder EnableRetryOnFailure(
     /// <param name="compatibilityLevel"><see langword="false" /> to have null resource</param>
     public virtual SqlServerDbContextOptionsBuilder UseCompatibilityLevel(int compatibilityLevel)
         => WithOption(e => e.WithCompatibilityLevel(compatibilityLevel));
+
+    /// <summary>
+    ///     Configures the context to use defaults optimized for Azure SQL, including retries on errors.
+    /// </summary>
+    /// <param name="enable">Whether the defaults should be enabled.</param>
+    public virtual SqlServerDbContextOptionsBuilder UseAzureSql(bool enable = true)
+        => WithOption(e => e.WithAzureSql(enable));
 }

src/EFCore.SqlServer/SqlServerRetryingExecutionStrategy.cs

@@ -12,7 +12,7 @@ namespace Microsoft.EntityFrameworkCore;
 /// </summary>
 /// <remarks>
 ///     <para>
-///         This strategy is specifically tailored to SQL Server (including SQL Azure). It is pre-configured with
+///         This strategy is specifically tailored to SQL Server (including Azure SQL). It is pre-configured with
 ///         error numbers for transient errors that can be retried. Additional error numbers to retry on can also be supplied.
 ///     </para>
 ///     <para>
@@ -30,6 +30,11 @@ public class SqlServerRetryingExecutionStrategy : ExecutionStrategy
 {
     private readonly HashSet<int>? _additionalErrorNumbers;
 
+    /// <summary>
+    ///     The default minimum time delay between retries for Azure SQL.
+    /// </summary>
+    protected static readonly TimeSpan DefaultMinDelayAzureSql = TimeSpan.FromSeconds(5);
+
     /// <summary>
     ///     Creates a new instance of <see cref="SqlServerRetryingExecutionStrategy" />.
     /// </summary>
@@ -138,6 +143,11 @@ public SqlServerRetryingExecutionStrategy(
         _additionalErrorNumbers = errorNumbersToAdd?.ToHashSet();
     }
 
+    /// <summary>
+    ///     Additional SQL error numbers that should be considered transient.
+    /// </summary>
+    public virtual IEnumerable<int>? AdditionalErrorNumbers => _additionalErrorNumbers;
+
     /// <summary>
     ///     Determines whether the specified exception represents a transient failure that can be
     ///     compensated by a retry. Additional exceptions to retry on can be passed to the constructor.
@@ -181,7 +191,9 @@ protected override bool ShouldRetryOn(Exception exception)
 
         return CallOnWrappedException(lastException, IsMemoryOptimizedError)
             ? TimeSpan.FromMilliseconds(baseDelay.Value.TotalSeconds)
-            : baseDelay;
+            : CallOnWrappedException(lastException, IsThrottlingError)
+                ? baseDelay + DefaultMinDelayAzureSql
+                : baseDelay;
     }
 
     private static bool IsMemoryOptimizedError(Exception exception)
@@ -204,4 +216,58 @@ private static bool IsMemoryOptimizedError(Exception exception)
 
         return false;
     }
+
+    private static bool IsThrottlingError(Exception exception)
+    {
+        if (exception is SqlException sqlException)
+        {
+            foreach (SqlError err in sqlException.Errors)
+            {
+                switch (err.Number)
+                {
+                    case 49977:
+                    case 49920:
+                    case 49919:
+                    case 49918:
+                    case 45319:
+                    case 45182:
+                    case 45161:
+                    case 45157:
+                    case 45156:
+                    case 41840:
+                    case 41823:
+                    case 40903:
+                    case 40890:
+                    case 40675:
+                    case 40648:
+                    case 40642:
+                    case 40613:
+                    case 40501:
+                    case 40189:
+                    case 39110:
+                    case 39108:
+                    case 37327:
+                    case 30085:
+                    case 25740:
+                    case 25738:
+                    case 22498:
+                    case 22335:
+                    case 17889:
+                    case 14355:
+                    case 10930:
+                    case 10929:
+                    case 9985:
+                    case 3950:
+                    case 3935:
+                    case 1404:
+                    case 1204:
+                    case 233:
+                    case -2:
+                        return true;
+                }
+            }
+        }
+
+        return false;
+    }
 }